Audion tube tester



May 21, 1935.A R. l.. TRIPLETT 2,001,945

Y AUDION TUBE TESTER Original FiledJan. l1, 1932 RAV Ll. TRIPLE'TT,

Patented May v21, 1935 s PAT AUDroN TUBETESTER l Ray L. Triple, Blanton, ohio Originalapplicatin January 11, 1932, Serial No.

585,937. Divided and this application March f 13, 1933, Serial No. 660,559 .Y Y

Y n 8Claims.

:This invention relates to a method of and ap- "paratusforitesting vacuum tubes/and particularly to methods and apparatus in which an alternating current source may be employed to en- I ergize all of the circuits of the tube.

, Audion tubesare usuallytested `byapplying different voltages to thegrid and determining the mutual conductance of the'tube bymeasuring themhange in theplate current `caused by the diierent grid voltages. In tubes of this kind the 'electron iiow is increased ordecreasedwithin defined limits by change of voltages appliedto the various elements. Electronsare attractedto theV plate within, a vcertain `definite -limit determinedby the :current through the filament and the bias voltages lupon the grid." Hence, within certain limits, the conductance ofthe `tube may' beidetermined byvarying the plate Voltage, the initial voltages applied to the other tube elements remaining unchanged.

In audion tubes the electron ow may be increased or decreased within defined limits by different voltages applied to the various elements. The electrons are attracted to the plate within specied limits, as the plate voltage becomes morepositive. Hence,within certain limits the conductance of a tube `may be determined by varying only the plate voltage, while the initial voltages applied to the other tube elements re- 30 main unchanged. kBy measuring the conductance of the tube under different conditions of plate voltage the worth of a tube can be obtained.

Itis my object to maintain the input into the tube or the grid conditions the same, and to change the applied potential of the loutput or plate circuit, and measuring the plate current with the two or more applied potentials and subtracting the difference to determine the value of the tube. In otherwords, by having a standard grid and lament condition and varying the plate condition I can determine the value of the tube.

This application is a division of my copending application, Ser. No. 585,937, filed January 11, 1932.

In the present drawing preferred embodiments of this invention are shown.

Figure 1 is a diagrammatic view of an alternating current tube tester inl which a battery circuit may be connected into the plate circuit.

Figure 2 is a view similar to Figure 1 but showing a iioating grid.

The numeral I is used to designate the primary of a Atransformer which is connected across a source of alternating current by two lines or wires 2 and `2a. The secondary of the transformer is indicated bythe numeral 3, and has extending therefrom wires or conductors 4, leading to a filament `5 of aradiant tube 6. This tube has an intermediate grid member I` connected to one of the'conductorsl by means of a conductor or wire 8, which is connected by means of a conductor or wire 9 to the wire 2 of the primary of the transformer.

A control grid II of the tubeA is connected by meansuof :a-line or conductor II)` torthe'con'- ductori 9. Theplate I2 of the tube has connected thereto a line I2a, which Vhasin ,it a milliameter I3. On the end ofthe line or. conductor I2a, remote from the plate I2, is a switch I4 which `is Ynormally in engagement with the contact point 15,011 one end `of a conductor I6 connected to the wire 2a of the .primary ,of the transformer.

Extending from the conductor I6 vis a conductor I1, which is connected to one side of a battery I8, which has connected to its other side a conductor I9. The conducto-r I 9 has on its end, remote from the battery, a contact point 20 which is adapted to be engaged by the switch I4 when it is pressed down. The plate circuit normally consists of the conductors VIIi and I2a, the plate I2,'1ament 5 andthe conductor 9 conneotedlacross the two conductors of the primary l coil of the transformer.

Under these conditions the full voltage of the primary circuit of the transformer passes through this circuit. The voltage of this circuit may have superimposed upon it the voltage of the battery I8. In order to superimpose upon the alternating current the current o-f the battery I8 the switch I4 is pressed down into engagement with the contact point 20, thereby causing an alternating voltage and a direct voltage to pass through the plate circuit. There may be, therefore, two different' voltages applied to the plate circuit, while the filament voltage and the grid voltage are maintained at constant values. 'I'he differences in the currents through the plate circuit are measured by the milliameter` I3. By

Y means of these'diiferences the quality and characteristic of the tube may be determined.

In Figure 2there is a iioating grid 2| and the conductor 9 is removed and its function accomplished by means of a conductor 22 connecting the primary of the transformer to the secondary of the transformer. In this Vform instead of the plate circuit including the conductor 9, it includes one of the wires or conductors 4 and the conductor 22. The application of the varying voltages to the plate circuit is eiiected in this form in the same manner that it is effected in the form shown in Figure 1, and variations in the current are registered by means of the milliameter I3.

It will be understood that I desire to comprehend within my invention such modications as come within the scope of my claims and my invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is: y

1. In an apparatus for testing audion tubes, an audion tube, a circuit supplied with current, a transformer associated therewith having its primary therein, a plate `circuit connected into one side of said circuit containing the primary' of the transformer, a switch in the plate .circuit, an additional source o-f potential, means for connecting it into said plate circuit by said switch,'and ameasuring instrument in said plate circuit whereby the differences in applied potentialto vthe plate may'beindicated on the measuringinstrument to show the condition of the tube.

`2. In an audion tube tester, a transformer having 'a secondary for energizing the coil and grdof the tube, a circuit connected across the primary of the transformer for providing a plate circuit lwith a definite voltage therein, battery means forsuperimposing' on said voltage another definite'voltage, and a measuring instrument in the plate circuit.

3. In an audion tube tester, a transformer l having a secondary energizing the filament and ther grid of the tube,'a circuit connected across the primary of the transformer through the plate circuit, means to superimposeuponthe alternating current in the plate circuit a direct current, and means to measure the currents.

4. In an audion tube tester, a transformer having a secondary forming the filament and the grid circuit, a circuit connected across the primary of the transformer through the plate of the tube, a battery circuit, means to cut the battery circuit into the plate circuit so that a direct current is superimposed upon the alternating current from the primary, and a measuring instrument for said currents.

5. In an audion tube tester, means to maintain a definite uniform filament and grid voltage, means to provide a denite alternating current to the plate, means to superimpose upon the alternating current adeiinite and predetermined direct current, andmeans to measure said currents.

6. In an audion tube tester, means to maintain a uniform filament and grid voltage, means to provide a denite alternating current yto the plate, a battery for superimposing on the alternating current a definite direct current, and means to measure said currents.

7. In an audion tube tester, means to supply a deiinite grid voltage, means to apply an alternating current to the plate andthe gridof the tube, means to superimpose upon the alternating current a definite direct current, and means to measure the currents.

8. The method of testing audion tubes which comprises energizing'the grid and the iilament circuits from an alternating current source, impressing upon the plate circuit an alternating voltage, superimposing upon `the alternating voltage a continuous voltage, and indicating the magnitudes ofthe plate currents. 

